Moving triplet quavers down to another staff converts them to regular quavers?

Moving these notes down with alt-m:


Gives this result:


I was expecting them to just become crochets, but it seems like it’s converting triplet quavers into regular quavers.

Where am I going wrong?

You are not selecting the “3” from the triplet. So what gets copied is the notes without their triplet “property” (so three quavers tied). I don’t think you can do what you want in one step. You’ll need to select the bottom notes of the treble staff, along with the triplets numbers, copy to staff below, then delete the bottom notes of treble staff.
Honestly, I would simply select the bass notes, press shift I and “8” to add the octaves :wink:

Ahh, yes I did try selecting the 3 as well but that made a massive mess. I think your method is much easier! :wink:

or, with the notes selected as the OPs picture, a simple alt-shift-left in insert mode (with 8ths grid) also could’ve done the trick!